The present invention relates generally to circuitry for arming and disarming an electronic device, and more particularly, to a method and circuit for isolating an activation circuit from an ignition circuit.
Flight and other operational characteristics of an unmanned vehicle or weapon system, such as a missile, are controlled via a guidance processor in conjunction with other electronics. The guidance processor activates squibs or ordnances to ignite propellant within a combustion chamber and selectively activates valves that obtain fuel from the combustion chamber to propel and direct the weapon system towards a target.
Various safety requirements are imposed on weapon systems to ensure safe handling and transportation and to ensure proper detonation of the weapon system. Weapon systems are typically designed to meet a single system malfunction tolerant requirement and provide a low probability of system malfunction.
Thus, as one safety measure, in many known weapon systems, various devices are used to isolate activation circuitry from ignition circuitry. The activation circuitry is determinative of when propellant is ignited and the ignition circuitry actually ignites the propellant in response to an enable signal from the activation circuitry. For example, typically within larger weapon systems, mechanical relays are employed to fully isolate activation circuitry from ignition circuitry, which is sometimes referred to as a firing train interruption. The mechanical relays are large in size and are of considerable weight.
A current desire exists to implement similar isolation circuitry within smaller weapon systems, such as within kinetic warheads, to isolate activation power from an ignition circuit or series of squibs. Unfortunately, use of mechanical relays and the like is not feasible within the confined available space of a kinetic warhead, as well as in other unmanned vehicles.
Also, unmanned vehicles commonly have stringent restrictions on maximum permissible weight without hampering vehicle performance, therefore, it is preferred that the isolation circuitry be relatively light in weight in order for proper flight operation performance.
Additionally, current control circuits of smaller unmanned vehicles can experience a bleed down situation, upon which digital electronics contained therein can be in an indeterminate state and can inadvertently ignite the squibs at an inopportune time. For example, when a supply voltage is inadvertently activated and remains in an xe2x80x9cONxe2x80x9d state, over time the supply voltage eventually drains and drops below a predetermined voltage level causing a guidance processor of the unmanned vehicle to function inappropriately.
It is therefore desirable to provide a circuit that meets the isolation requirements for safely isolating an activation circuit from an ignition circuit within a smaller scale unmanned vehicle that is relatively small in size, relatively light in weight, and provides a low probability of system malfunction.
The present invention provides a method and circuit for isolating an activation circuit from an ignition circuit. An ignition isolating interrupt control circuit is provided. The circuit includes a main transition circuit isolating a first activation circuit from an ignition circuit. The main transition circuit includes a source terminal that is electrically coupled to and receives a first source power from the first activation circuit. An input terminal is electrically coupled to a second activation circuit and receives an activation signal. An output terminal is electrically coupled to the ignition circuit and receives and supplies the first source power to the ignition circuit in response to the activation signal. A power source monitor cutoff circuit including a comparator is electrically coupled to the first activation circuit and to the ignition circuit and disables the ignition circuit when a source voltage, level is less than a predetermined voltage level.
One advantage of the present invention is that it safely isolates an activation circuit from an ignition circuit within relatively smaller unmanned vehicles and accounts for bleed down situations.
Another advantage of the present invention is that it provides an ignition isolating interrupt control circuit that is relatively small in size, relatively light in weight and inexpensive, and yet durable.
Furthermore, the present invention has a low probability of system malfunction, which is lower than what is typically required of such vehicles.
Moreover, the present invention provides an ignition isolating interrupt control circuit with increased malfunction tolerance.